I'd encourage you to head to your local REIA's and even BP meetups as well.

If you would like to spend some time on the subject, I encourage you to look at the inventory levels over the last 10 or more years vs closings per month.

The two other offers were:1. cash offer of $45,0002. owner financing for $52,000 with $10,000 down and $600 for 70 monthBTW, meanwhile, we have sold the house with a wrap $120,000, with$12,000 down and $108,000 financed at 8% for 18 years.Thanks you all for your encouragements!

Because of this I'd encourage you not to let go of your license.

I am doing a coaching program at the moment, and am being encouraged to seek out cash buyers first, and then look for properties that meet their needs. 

Some encourage 2 family homes aka BP househacking!

I would encourage you to partner w/ a title company that has experience closing on HUD deals next time.  

on the subject of your mortgages, i would check with local smaller named banks for a portfolio lender, also see if their is any way to work a heloc from your properties, private money lenders would be a good avenue, also seller finance is a great way to get more properties, the hardest part of REI is the more you try to do the worse banks are to deal with and creative financing comes into play, i would also encourage if you have not already jump into searching for funding, seller finance, creative finance on BP and listen to the podcasts, read into the forums ect. to get your creative gears moving. 

Thank you everyone, I sincerely appreciate the encouragement and tips!  

Sounds like this is what you're doing, but I encourage you to let go of the negative, do what you can do now to make things right, and use your new found wisdom to make the next investment a great one!